B&W to W&B
18-Oct-95 14:58:41
Sb: #195916-B&W to W&B
Fm: James Coulter[Mindscape] 73670,677
To: Stephen Grisez 72730,3634
The Alpha vs. Psuedo Alpha is sort of a non-issue for technical reasions.
Here's why:
A 24 bit TGA file has 8 bits per pixel for each of red, green, and blue colors
respectively, hence 24 bits per pixel. Each set of 8 bits is called a Channel.
Hence, an 8-bit red channel, an 8-bit green channel, and blue. A TGA file with
an Alpha Channel is a 32 bit format. 24 bits per pixel for the three color
channels RGB, and 8 more bits per pixel for Alpha data.
These 8 bits for Alpha can be thought of as 256 grayscale levels. 0 (black)
being transparent; 255 (white) being opaque, with a linear gradient of
transparency in between. The information in the 8 bits are identical to an
8-bit grayscale FLC file. 8 bits is 8 bits no matter which way you look at it.
As you already know, 3DS can either use the Alpha Channel of the TGA file or a
user-supplied Psuedo Alpha as you call it. Providing the data is the same,
there will be absolutely no difference in the finished composite.
Using the FLC to create the Alpha Channels for a series of TGA files gains
nothing in terms of quality. It _does_ make compositing simpler because the
alpha data is carried with the TGA file. This is usefull if you expect to
re-use the files often. Otherwise, it's an unnecessary additional step in a
"one-off" animation.
BTW, good erasing technique! You could use it with TGA files too. Erase and
save, etc., etc., then create a reverse-numbered IFL file.
— James — Choreo Motion —